"I Breathe But I Can't Catch My Breath..." Unger wrote. "Schoep passed yesterday. More information in the days ahead."

The bond between Schoep and Unger captivated tens of thousands of animal lovers when their photo and story began circulating
nearly a year ago. Last July, Unger feared that he was mere days from
needing to put then-19-year-old Schoep down. In anticipation of his
loss, he asked a friend to take one last photo of them together.

That friend, photographer Hannah Stonehouse Hudson,
met them at Lake Superior, where Unger liked to help Schoep float to
take pressure off his arthritic joints. She captured a photo of the two
of them in the lake and posted it on her Facebook page on Aug. 1.

That
image ricocheted around the world and resulted in an outpouring of
online donations and support. The help Unger received allowed him to
afford treatments to alleviate his dog's condition.

"As best as I can guess, the treatments have turned back the clock on his life about a year-and-a-half to two years," Unger told TODAY.com
in September 2012. "I've taken him for walks on trails that we haven't
been on in three years. He's not dragging his back legs like he was
before. To be able to do that again with him, words can't even describe
the feeling."

Just
this Monday, Unger posted a happy update about Schoep on Facebook along
with a photo of the shepherd mix falling asleep in the sunshine,
surrounded by bright yellow flowers:

"A fantastic day we had. Up
early to walk and go to the beach, eat, nap, go shopping, eat, laundry,
go to the beach, eat, nap and one more walk. All without the humidity,
that's what made it fantastic - especially for Schoep!"